1. Field of the Invention
The present invention relates to the field of telecommunications. More particularly, the present invention relates to cellular, Personal Communications Services (PCS) and other wireless network systems, and mobile stations having intelligent roaming and over-the-air programming features.
2. Related Application Information
The present disclosure relates to subject matter contained in U.S. patent application Ser. No. 08/828,172 (filed on Mar. 18, 1997), which is expressly incorporated herein by reference in its entirety.
3. Background and Material Information
The use of wireless or mobile communication devices has increased greatly in recent years. Mobile and cellular telephones have enabled mobile station users to roam over large geographic areas while maintaining immediate access to telephony services. Mobile stations include portable units, units installed in vehicles and fixed subscriber stations. Mobile stations comprising cellular telephones or wireless handsets are operable in cooperation with cellular or Personal Communications Services (PCS) communications systems. Cellular communication systems (wireless carriers) typically provide service to a geographic market area by dividing the area into many smaller areas or cells. Each cell is serviced by a radio transceiver (i.e., a transmitter-receiver base station or cell site). The cell sites or base stations may be connected to Mobile Telephone Switching Offices (MTSOs) or Mobile Switching Centers (MSCs) through landlines or other communication links, and the MTSOs may, in turn, be connected via landlines to the Public Switched Telephone Network (PSTN).
FIG. 1 illustrates the basic components of a conventional cellular network. As shown in FIG. 1, a mobile station 38 may place or receive calls by communicating with a cell site 30 or a cell site 40, depending upon the geographic location of the mobile station and the cell coverage area that is provided by each cell site (i.e., cell coverage area 35 of cell site 30 or cell coverage area 45 of cell site 40). For purposes of illustration, mobile station 38 is depicted in FIG. 1 as being able to communicate with either cell site 30 or cell site 40, even though the mobile station is not illustrated as being located within cell coverage area 35 or cell coverage area 45. Under normal operating conditions, the extent to which mobile station 38 will be able to communicate with cell site 30 or cell site 40 will depend on the geographic location of the mobile station and the size of the cell coverage area of each cell site. Further, although only two cell sites are depicted in FIG. 1, the entire cellular network may include, for example, more than two cell sites. In addition, more than one cell site may be connected to each MTSO.
Mobile station 38 may include a conventional cellular telephone unit with a transceiver and antenna to communicate by, for example, radio waves with cell sites 30 and 40. Various air-interface technologies may be implemented to facilitate communication between the mobile station and the cell sites. In addition, various service offerings may be made available to mobile station users. Cell sites 30 and 40 may both include a radio transceiver and be connected by landlines 16 or other communication links to MTSOs 24 and 28. The PSTN 12 is also connected to each MTSO 24 and 28 by landline 16 or other communication links.
The MTSOs 24 and 28 may be conventional digital telephone exchanges that control the switching between the PSTN 12 and the cell sites 30 and 40 to provide wireline-to-mobile, mobile-to-wireline and mobile-to-mobile call connectivity. The MTSOs 24 and 28 may also (I) process mobile station status data received from the cell site controllers; (ii) handle and switch calls between cells; (iii) process diagnostic information; and (iv) compile billing information. The transceiver of each cell site 30 and 40 provides communications, such as voice and data, with mobile station 38 while it is present in its geographic domain. The MTSOs 24 and 28 may track and switch mobile station 38 from cell site to cell site, as the mobile station passes through various coverage areas. When mobile station 38 passes from one cell to another cell, the MTSO of the corresponding cell may perform a "hand-off" that allows the mobile station to be continuously serviced.
In the current North American cellular system, any given market area may be serviced by up to two competing service providers of cellular air time communication services (wireless carriers). By Federal Communications Commission (FCC) regulations, the two competing wireless carriers are assigned different groups of frequencies through which services are provided. A frequency set typically includes control channels and voice channels. The control channels are used for preliminary communications between a mobile station and a cell site for setting up a call, after which a voice channel is assigned for the mobile station's use on that call. The assigned frequency sets are generally referred to as "A band frequencies" and "B band frequencies". Typically, the A band frequencies are reserved for non-wireline service providers, while the B band frequencies are reserved for the incumbent wireline service providers. While each frequency set for a given cellular service market area is assigned to only one service provider, in different market areas the same frequency set may be assigned to different service providers or companies.
Depending upon which wireless carrier the user of the mobile station subscribes to, the home frequency set of the user may correspond to the A frequency band or the B frequency band. Whenever a call is placed by the mobile station, the unit will ordinarily attempt to use the home frequency set to establish the call. If a call is handled outside of the user's home market area, then the unit is said to be "roaming" and service will be attempted through a frequency set of a non-home service provider. Typically, the user's home service provider will have a roaming agreement or reciprocal billing arrangement with the non-home service provider to permit service to be extended to the user's mobile unit when it is roaming in the non-home service provider's market area.
Whereas cellular typically operates in the 800-900 MHZ range, PCS is expected to operate in the 1.5 to 1.8 GHz range. In North America, the FCC has awarded PCS licenses in six additional bands (i.e., the A-F carrier blocks or bands). PCS covers a broad range of individualized telecommunication services that let users communicate irrespective of where they are located. With PCS, personalized numbers are assigned to individuals rather than to the mobile stations, and call completion is performed regardless of the location of the user. PCS may be implemented through conventional macro-cellular techniques or through Personal Communications Networks (PCN) that utilize light, inexpensive handheld handsets and communicate via low-power antennas that are intended to operate in a similar fashion to that of large scale cellular telephone networks, but operate within small geographic or microcellular areas. It is anticipated that PCNs will operate within the same frequency band in most countries (e.g., 1850-1990 MHZ), while cellular systems will operate in different frequency bands in various countries.
The mobile station may include a memory device, such as a number assignment module (NAM), in which an assigned phone number and a system identification code (SID) and/or System Operator Code (SOC) is stored to uniquely identify the home service provider for the unit. In the North American cellular system, each provider within a market area is assigned a distinct, fifteen bit SID. IS-136 service providers are also assigned a 12-bit SOC for use throughout all their market areas. In Europe, on the other hand, the Global System for Mobile Communications (GSM) standard (see, for example, Recommendation GSM 02.11, Service Accessibility, European Telecommunications Standards Institute, 1992) defines a process for network selection based on the mobile station reading the GSM equivalent of the SID, called the Public Land Mobile Network (PLMN) identity.
The SID or equivalent system identification number is broadcast by each wireless carrier and is used by the mobile station to determine whether or not the mobile station is operating in its home network or if it is operating in a roaming condition. The mobile station makes this determination by reading the SID broadcast in the cellular market area where it is located, and comparing it to the home SID stored in the NAM of the cellular phone unit. If the SIDs do not match, then the mobile station is roaming, and the mobile station must attempt to gain service through a non-home service provider. Due to the imposition of a fixed surcharge or higher per unit rate, the airtime charges when the mobile station is roaming are customarily higher than when it is operating within its home network.
Operation under a roaming condition is often under the control of the mobile station user. The user can select whether the mobile station will operate in a Home System Only, A Band Only, B Band Only, A Band Preferred, or B Band Preferred operating mode. The user typically controls the system preference and mode operation through menu choice or selection. This current method of roaming control is conventionally known as "Preferred System Selection". In the most common roaming situation, the mobile station remains on the same band as the home cellular network. That is, if the mobile station is homed to a cellular network with an odd numbered SID (which is normally assigned to an A band cellular service provider), then the mobile station will obtain service from the A band cellular service provider when roaming.
Occasionally, the home service provider will program a mobile station with negative SIDs. Negative SIDs correspond to SIDs on which the mobile station should not obtain service. Negative SIDs may be used, for example, if roaming agreements are not in place between different cellular service providers. An example of a mobile station that utilizes negative SIDs is disclosed in BLAIR, U.S. Pat. No. 4,916,728. As an alternative to negative SIDs, some mobile stations are programmed with positive or preferred SIDs. Positive or preferred SIDs are SIDs on which the mobile station should attempt to obtain service when selecting a cellular carrier frequency. An example of a mobile station that utilizes preferred SIDs is disclosed in BARBER et al., U.S. Pat. No. 5,442,806. The use of preferred SIDs facilitate the selection of a preferred service provider when the mobile station is roaming.
With the maturation of mobile communication, a variety of advanced services or service offerings have become available to mobile station users. For example, mobile station users may now elect to subscribe to messaging services (such as voice mail, text messaging or Short Message Service (SMS)), or other services such as call waiting indication, voice privacy, etc. SMS and other forms of teleservices may be provided to a mobile station via a message center connected to the cellular network. However, when roaming in another market area, certain wireless carriers in that market may not support all of the advanced services to which the user subscribes. Consequently, when roaming, the user may lose use of some or all of the advanced services that the user is accustomed to using.
Moreover, some large companies have come to depend upon the use of mobile stations and wireless communications. As a result of the large volume of such usage, they have set up corporate accounts with wireless carriers. These accounts are referred to by the wireless carriers as National Accounts. Preferred roaming rates may be negotiated for a National Account with particular wireless carriers in certain geographic market areas. Thus, when a mobile station roams to one of these market areas, the National Account subscriber may prefer a different wireless carrier from the carrier preferred by the mass market. Furthermnore, a corporation may require its personnel to subscribe to particular advanced services, e.g., a messaging service so the personnel is always reachable. Conventional mobile station equipment and systems do not permit a corporation to control which carrier roaming personnel will use in order to obtain beneficial rates and to receive selected required advanced services.
Thus, there is a need in the cellular and mobile network industries to provide some form of intelligent or automatic roaming in which the mobile station obtains service on the cellular network with which the home cellular service provider has the best roaming agreement (or the cellular service provider's own network in the roaming area, if it is not in the same band as the home system), and/or which supports the services the user requires. Two factors have primarily led to this need. First, large cellular service providers rarely operate in the same band in all markets. Second, cellular service providers have chosen to offer different advanced technologies or services. Consequently, the mobile station may have to change bands to obtain the required services.
Further, there is a need to provide intelligent roaming capabilities for a mobile station which will not require any changes to present network interface standards (e.g. IS-41) or air interface standards (e.g., IS-136, IS-91A, IS-95). Such features are desirable in order to pen-nit new intelligent roaming capabilities to be readily utilized by a mobile station and to allow seamless integration of such capabilities without modification to present industry standards. For more information on network interface standards such as Interim Standard 41 (IS-41), see, for example, TIA/EIA-IS-41.5-C, Cellular Radiotelecommunications Intersystem Operations: Signaling Protocols, Telecommunications Industry Association, February 1996. For more information on air-interface standards such as Interim Standards 95 and 136 (IS-95 and IS-136), see, for example, TIA/EIA-IS-95-A, Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular Systems, Telecommunications Industry Association, May 1995; TIA/EIA-IS-136.1-A, TDMA Cellular/PCS-Radio Interface-Mobile Station-Base Station Compatibility-Digital Control Channel, Telecommunications Industry Association, October 1996; TIA/EIA-IS-136.2-A, TDMA Cellular/PCS-Radio Interface-Mobile Station-Base Station Compatibility-Traffic Channels and FSK Control Channel, Telecommunications Industry Association, October 1996; and TIA/EIA/IS-136.1-A-1, Addendum No. 1 to TIA/EIA/IS-136.1-A, Telecommunications Industry Association, November 1996.
Another desirable feature is to provide over-the-air programming of a mobile station to permit reprogramming of the mobile station with new intelligent roaming information as it becomes available. Such a feature would permit the "intelligence" that is incorporated into the mobile station to be updated and stored with ease, without requiring the user to bring the mobile station to a technician or operator for reprogramming.